Chair back



FIG. 1 is a front perspective view of our chair back design;

FIG. 2 is a rear perspective view of the chair back design shown in FIG. 1;

FIG. 3 is a left side perspective view of the chair back design shown in FIG. 1;

FIG. 4 is a right side view of the chair back design shown in FIG. 1;

FIG. 5 is a front view of the chair back design shown in FIG. 1;

FIG. 6 is a left side view of the chair back design shown in FIG. 1;

FIG. 7 is a rear view of the chair back design shown in FIG. 1; and,

FIG. 8 is a top view of the chair back design shown in FIG. 1.

The broken lines shown in FIG. 1 are for illustrative purposes only and form no part of the claimed design. 

We claim the ornamental design for a chair back, as shown and described. 